Surgical stapling instrument

ABSTRACT

A surgical stapling instrument comprises a frame having a body portion and a handle. A staple fastening assembly is provided in the distal region of the instrument and includes a cartridge device, which comprises at least one closed row ( 10, 12 ) of staples, and an anvil. The anvil is movable relative to the cartridge device and is adapted to cooperate with the cartridge device for forming the ends of the staples exiting from the cartridge device. A knife, which has a closed cutting edge, is contained within the cartridge device and is positioned such that there is at least one closed row ( 10, 12 ) of staples on the outside of the cutting edge. It can be moved towards the anvil. The line along which the closed row ( 10, 12 ) of staples is arranged has a stepped shape, leaving a plane perpendicular to the longitudinal axis of the staple fastening assembly, such that this line has a larger total length than the projection of this line onto this plane. This provides a greater flexibility of the anastomotic site and less tension during instrument removal, alleviating the incidence of clinical complications.

BACKGROUND OF THE INVENTION

The invention relates to a surgical stapling instrument, which can beused for applying surgical staples or clips to tissue and in particularfor performing an anastomosis.

Generally, in the performance of a surgical anastomotic staplingoperation, two pieces of lumen or tubular tissue, e.g., intestinaltissue, are attached together by a closed row of staples. In performingthe anastomosis with a surgical stapling instrument, the two pieces oftubular tissue are clamped together between an anvil provided with anarray of staple forming grooves and a staple holder or cartridge deviceprovided with a plurality of staple receiving slots arranged in a closedrow or array in which the staples are received. A staple pusher isadvanced to drive the staples into the tissue and form the staplesagainst the anvil. Moreover, a circular knife is advanced to cut theexcess tissue clamped between the anvil and the staple holder. As aresult, the donut-shaped section of tissue is severed from each lumenand remains on the anvil shaft. The tubular tissue joined by the closedrow of staples is unclamped by moving the anvil relative to the stapleholder, usually by advancing the anvil shaft distally to move the anvilaway from the staple holder. The stapling instrument is removed bypulling the anvil through the opening between the pieces of tubulartissue attached by the array of staples.

Surgical stapling instruments of this kind are well-known. For example,U.S. Pat. No. 5,205,459 describes such an instrument in detail. Asusual, the closed row of staples of the instrument disclosed has aplanar, circular shape. U.S. Pat. No. 5,275,322 is a document showing abasic version of a circular stapling instrument.

Although the use of the known surgical stapling instruments is verybeneficial and greatly facilitates the performance of an anastomosis, itinvolves some problems. Often it is difficult to retract the instrumentfrom the site of the operation, because it is difficult to move theanvil through the opening bordered by the closed row of staples, whichis somewhat stiff. Moreover, after the operation, the incidence ofclinical stenosis at the site of the anastomosis is not rare.

In order to overcome these problems, it is proposed in WO 01/54594 A1 toarrange the closed row of staples in a wavy shape which leaves a planeperpendicular to the longitudinal axis of the instrument. In this way,the line along which the staples of the closed row are arranged has alarger total length than the projection of this line onto a plane.Consequently, the length of an anastomosis seam is larger than that ofan anastomosis performed by means of conventional stapling instrument.Because of this increased length, the anastomotic site can assume alarger diameter and is more flexible, so that the anvil can be easilymoved through the opening created by the knife, and the surgicalstapling instrument can be retracted at the end of the surgery moreeasily. Additionally, the resulting larger anastomosis lumen willalleviate the incidence of clinical complications. On the other hand, ifit is sufficient that the total length of the closed row of staples iscomparable to that provided by a conventional stapling instrument, thisinstrument can be designed in a more compact size such that it can beeasier inserted into a tubular organ and removed therefrom.

For optimum performance of the stapling instrument disclosed in WO01/54594 A1, the individual staples are expelled from the cartridgedevice in a direction perpendicular to the local slope of the wavyshape, which generally is not parallel to the longitudinal axis of theinstrument. This requires a more complicated staple drive mechanismwhich experiences load components transverse to the longitudinal axis ofthe instrument. Moreover, the alignment of the staple-forming grooves atthe anvil to the pointed ends of the staples exiting from the cartridgedevice is only correct for a certain distance between the cartridgedevice and the anvil, i.e. for a certain thickness of the tissue clampedbetween the cartridge device and the anvil, which results in a loss ofvariability with respect to the tissue thickness.

EP 1 090 592 A1 discloses a linear surgical stapler, in which the anvilhas two staple-forming surfaces which are spaced with respect to eachother in the staple expelling direction. In this way, the anvil isformed with a stiffening rib which generally strengthens the cantileverdesign of the linear stapler.

BRIEF SUMMARY OF THE INVENTION

The object of the invention is to provide a surgical stapling instrumentfor performing an anastomosis, which has the advantages of theinstrument disclosed in WO 01/54594 A1, but allows for a simpler designand generally exhibits less restrictions with respect to tissuethickness.

The surgical stapling instrument according to the invention comprises aframe having a body portion and a handle as well as a staple fasteningassembly in the distal region of the instrument. The staple fasteningassembly includes a cartridge device which comprises at least one closedrow of staples, and an anvil. The anvil is movable relative to thecartridge device and is adapted to cooperate with the cartridge devicefor forming the ends of the staples exiting from the cartridge device. Amoving device is adapted to move the anvil relative to the cartridgedevice. A staple driving device is adapted to drive the staples out ofthe cartridge device towards the anvil. A knife, which has a closedcutting edge, is contained within the cartridge device and is positionedsuch that there is at least one closed row of staples on the outside ofthe cutting edge. A knife actuating device is adapted to move the knifetowards the anvil. So far, these features are known from the prior art,e.g., from U.S. Pat. No. 5,205,459.

According to the invention, the line along which the closed row ofstaples is arranged has a stepped shape, leaving (i.e., not beingconfined to) a plane perpendicular to the longitudinal axis of thestaple fastening assembly, such that said line has a larger total lengththan the projection of said line onto said plane. Preferably, thisprojection is circular.

Thus, the line along which the closed row of staples is arranged has alarger total length than the line defining the planar array of staplesof a conventional prior art surgical stapling instrument in which thecartridge device has about the same size. Consequently, similar to theinstrument disclosed in WO 01/54594 A1, the length of the anastomosisseam is larger than that of an anastomosis performed by means of aconventional stapling instrument. Because of this increased length, theanastomotic site can assume a larger diameter and is more flexible, sothat the anvil can be easily removed through the opening created by theknife, and the surgical stapling instrument can be retracted at the endof the surgery more easily. Additionally, the resulting largeranastomosis lumen will alleviate the incidence of clinicalcomplications. On the other hand, if it is sufficient that the totallength of the line along which the closed row of staples is arranged iscomparable to that provided by a conventional stapling instrument, theinvention allows for the use of a smaller instrument, which generallycan be more easily inserted into the tubular organ and removedtherefrom.

So far, the advantages of the surgical stapling instrument according tothe invention are similar to those of the instrument disclosed in WO01/54594 A1.

Additional advantages result from the stepped shape of the line alongwhich the closed row of staples is arranged. In particular, this allowsfor a design in which a local flat area, which is normal to thelongitudinal axis of the instrument, is created for each staple. Byapplying a simple conventional axial drive mechanism, the staple drivingdevice can be adapted to drive the staples out of the cartridge devicesuch that each staple is moved essentially in parallel to thelongitudinal axis of the staple fastening assembly, which is the optimumdirection in view of the stepped shape of the closed row of staples.Such kind of drive mechanism avoids undesired transverse loads.Moreover, the pointed ends of staples exiting from the cartridge devicestay aligned to the staple-forming grooves provided at the anvil,irrespective of the actual distance between the anvil and the cartridgedevice or the thickness of the tissue clamped between the anvil and thecartridge device. In other words, any anvil deflection or any stapleheight adjustability will not adversely effect staple location. When asimple axial drive mechanism is employed, the stroke or actuatingbehaviour of conventional instruments can be maintained, which is anadvantage because surgeons are familiar with it. Finally, the inventionallows for the application of existing circular stapler platforms, i.e.of existing components like frame, moving device, and staple drivingdevice, and therefore saves considerable costs.

Preferably, the anvil has a stepped staple-forming surface which matchesthe stepped shape of the line along which the closed row of staples isarranged.

Whereas it is conceivable that the knife has a conventional(cylindrical) basic shape with a circular cutting edge, in a preferredversion of the invention the line defining the cutting edge of the knifehas a stepped shape and runs essentially in parallel to the line alongwhich the closed row of staples is arranged. In this design, the knifehas to be moved by a short distance only in order to completely cut thetissue clamped between the cartridge device and the anvil.

In an advantageous version of the invention, the staples of a closed rowof staples are arranged at different positions, measured along thelongitudinal axis of the staple fastening assembly. In this way, thestaples are located at different steps of the stepped shape of theclosed row of staples. Alternatively, or with respect to another closedrow of staples, the staples of a closed row of staples can be arrangedwith gaps between adjacent staples, wherein each gap is defined by arecess in the surface of the cartridge device, and the anvil has aprotrusion fitting into that recess. Or the staples can be arranged withprotrusions between adjacent staples, wherein each protrusion emergesfrom the surface of the cartridge device, and the anvil has a recess foraccomodating that protrusion. A corresponding closed row of stapleshaving both protrusions and gaps or recesses between different pairs ofadjacent staples is conceiveable as well. Thus, the line along whichsuch closed rows of staples are arranged has a stepped shape, since thisline also follows the gaps or protrusions, although the staplesthemselves may be located all in the same plane.

As already mentioned, in a preferred version of the invention, thestaple driving device is adapted to drive the staples out of thecartridge device such that each staple is moved essentially in parallelto the longitudinal axis of the staple fastening assembly. This allowsfor a simple, reliable and less expensive design of the surgicalstapling instrument. Preferably, the staple driving devices comprisespushers for driving the staples. For adjustment to the stepped shape ofthe closed row of staples, the pushers can have different lengths. In anadvantageous version, the pushers are integrally combined in a sleevestructure. Providing pushers of different lengths allows for a simpledesign in which the staple driving device is adapted to drive thestaples of a closed row of staples essentially simultaneously out of thecartridge device. Such actuating behaviour maintains the stroke of aconventional stapling instrument.

Preferably, there are at least two closed rows of staples, wherein thestaples of adjacent rows are staggered with respect to each other. Thestaggered arrangement of the staples does not contradict the basic ideaof the stepped shape of the closed rows of staples, which will becomeevident from the embodiment described below in more detail. Ananastomosis seam containing two rows of staggered staples is tight andsafe.

The anvil can comprise a counterpart adapted to accommodate the cuttingedge of the knife. The counterpart preferably matches the stepped shapeof the anvil and/or the knife. Such counterparts, which exert a reactionforce onto the tissue during the cutting action and are cut by theknife, are generally known in the prior art, see, e.g., U.S. Pat. No.4,289,133.

In an advantageous version of the invention, the staple fasteningassembly is removably mounted in the distal end region of the bodyportion. This enables, e.g., the staple fastening assembly to beexchanged during the surgical operation or to be designed as adisposable part (whereas the frame including a major part of themechanical components is sterilizable and reusable). Moreover, thecartridge device can comprise a removable cartridge containing thestaples, such that, e.g., an empty cartridge can be replaced by a freshone, if required, or the cartridge device can be designed as a re-usablecomponent. Preferably, the anvil is removable as well, which is alsoessential for certain surgical techniques. To this end, the anvil cancomprise a shaft fitting onto a peg protruding from the cartridgedevice. The peg preferably comprises a mandrel which is useful forpiercing tissue in certain surgical techniques. These features aregenerally known from the prior art surgical stapling instruments.

The term “staple” is used herein in a very general sense. It includesmetal staples or clips, but also surgical fasteners made of syntheticmaterial and similar fasteners. Synthetic fasteners usually have acounterpart (retainer member) held at the anvil. In this sense, the term“anvil” also has a broad meaning which includes, in the case of two-partsynthetic fasteners, the anvil-like tool where the retainer members areheld, and similar devices.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is described in more detail by means ofan embodiment. The drawings show in

FIG. 1 a side view of the staple fastening assembly of an embodiment ofthe surgical stapling instrument according to the invention,

FIG. 2 an isometric view onto an end part which forms the distal surfaceof the cartridge device of the staple fastening assembly of FIG. 1,

FIG. 3 an isometric view of the distal portion of the staple drivingdevice of the embodiment,

FIG. 4 an isometric view onto the staple-forming surface of the anvil ofthe embodiment of the stapling instrument,

FIG. 5 an isometric view onto the staple-forming surface of the anvil ofanother embodiment of the stapling instrument.

FIG. 1 is a side view of the staple fastening assembly 1 which forms thedistal portion of a surgical stapling instrument. The staple fasteningassembly 1 includes a cartridge device 2 (which comprises, in theembodiment, two closed rows of staples) and an anvil 4. The anvil 4 ismounted at the distal end of a shaft 5 and can be moved relative to thecartridge device 2, i.e. along the longitudinal axis of the staplefastening assembly 1, in order to adjust the size of the gap between theanvil 4 and the cartridge device 2.

The cartridge device 2 comprises a housing 6 which contains the staples,a circular knife, as well as components of a moving device (adapted tomove the anvil 4 relative to the cartridge device 2), a staple drivingdevice (adapted to drive the staples out of the cartridge device 2towards the anvil 4), and a knife actuating device (adapted to move theknife towards the anvil 4). The end face of the cartridge device 2, i.e.the surface from which the staples exiting from the cartridge device 2are expelled towards the anvil 4, is formed in an end part 7 insertedinto the circumferential wall of the housing 6.

The staple fastening assembly 1 can be removably mounted on a shaft ofthe stapling instrument by means of a coupling 8 provided at theproximal end region of the cartridge device 2. The terms “proximal” and“distal” relate to the view of the person operating the staplinginstrument.

Generally, the overall design and the mechanical components, drivemechanisms and safety features of the surgical stapling instrument areas in a conventional circular stapling instrument; the three-dimensionalshape of the staple lines and some details of the staple driving device,however, are different, as explained in the following.

FIG. 2 shows the end part 7 in an isometric view. The distal surface ofthe end part 7 comprises slots from which the staples are expelledtowards the anvil 4 when the stapling instrument is “fired”. These slotsare arranged in two closed rows, thus defining a first closed row 10 ofstaples (the outer one in FIG. 2) and a second closed row 12 of staples(the inner one in FIG. 2).

Three of these exit slots of the first closed row 10 are designated bythe reference numerals 14, 15, and 16. As shown in FIG. 2, the exitslots 14, 15, and 16 and all the other exit slots of the first closedrow 10 lie in the same plane, i.e. a plane perpendicular to thelongitudinal axis of the staple fastening assembly 1. Between the exitslots 14 and 15, there is a gap or recess 18, whereas a protrusion 19emerges from the area between the exit slots 15 and 16. This pattern isrepeated along the circumference of the first closed row 10. In thisway, the line along which the first closed row 10 of staples isarranged, i.e. the line around the first closed row 10 following thesurface topography of the end part 7 and descending into the recess 18and ascending around the protrusion 19, has a stepped shape. It is thisline which defines, in the area of the first closed row 10, the tissuecontact between the cartridge device 2 and the anvil 4 when the staplinginstrument is operated.

In a similar manner, the line along which the second closed row 12 ofstaples is arranged has a stepped shape as well. In this case, however,the exit slots of the staples are located in two different planes, eachperpendicular to the longitudinal axis of the staple fastening assembly1. As shown in FIG. 2, exit slots 20 and 22 are in the same plane whichis more distal than the plane of the exit slots of the first closed row10. Exit slot 21, which is arranged between the exit slots 20 and 22, islocated in the other plane and is more proximal than the exit slots ofthe first closed row 10. This pattern is repeated along thecircumference of the second closed row 12. In the embodiment, the peaksof the protrusions 19 are in the plane of the exit slots 20 and 22,whereas the grounds of the recesses 18 are in the plane of exit slot 21.Exit slot 21 and the corresponding exit slots of the second closed row21 are radially aligned with the recesses 18. As shown in FIG. 2, thestaples of the first closed row 10 and the staples of the second closedrow 12 are staggered with respect to each other.

In FIG. 2, a staple guide part 24 is located below the distal surface ofthe end part 7. The staple guide part 24 comprises guide slots 26 forguiding the staples of the first closed row 10 and guide slots 28 forguiding the staples of the second closed row 12. Each of theses guideslots 26, 28 accommodates one staple, the pointed ends of the staplefacing the corresponding exit slot. The staple guide part 24 as well asthe end part 7 are preferably made of a medical grade resin by injectionmoulding and may be manufactured as one component.

The circular knife, which is not shown in the figures, is guided at theinner periphery of the end part 7. It is moved in distal direction whenthe stapling instrument is actuated, as usual with conventional circularstaplers. In the embodiment, the cutting edge of the knife has a steppedshape which essentially follows the stepped shape of the line alongwhich the second closed row 12 of staples is arranged.

FIG. 3 shows the distal portion 30 of the staple driving device of thestapling instrument. In the embodiment, this portion is designed as anintegrally moulded sleeve structure. It includes an actuator shaft 32distally ending at a base 34 which is reinforced by means of ribs 35.The proximal end of the actuator shaft 32 is coupled to an actuating rodinside the shaft of the stapling instrument when the staple fasteningassembly 1 is mounted to the distal end of this shaft. When theinstrument is “fired”, i.e. when an actuating trigger located at thehandle of the instrument is operated, the actuating rod is moved indistal direction, thus pushing the sleeve structure 30 in distaldirection as well.

For each staple, the staple driving device 30 comprises a pusherprotruding in distal direction and parallel to the longitudinal axis ofthe staple fastening assembly 1. These pushers are arranged in two rows,i.e. the outer pushers 36 for the first closed row 10 of staples and theinner pushers 38 and 39 for the second closed row 12 of staples. In theassembled state of the staple fastening assembly 1, the pushers 36 areguided in the guide slots 26, whereas the pushers 38 and 39 are guidedin the guide slots 28. As shown in FIG. 3, all of the pushers 36 havethe same length, but the pushers 39 are shorter than the pushers 38. Theend side of each pusher 36, 38 and 39 abuts at the crown of a staplesuch that the staples are expelled from the exit slots of the firstclosed row 10 and the second closed row 12 when the instrument is fired.

The shorter pushers 39 are assigned to exit slot 21 and thecorresponding exit slots of the second closed row 12, whereas the longerpushers 38 are assigned to the exit slots 20, 22 and the other exitslots in the more distal plane for the second closed row 12. The lengthof the pushers 36 is between that of the pushers 38 and 39,corresponding to the location of the exit slots of the first closed row10. This design results in an almost simultaneous exit of all staplesfrom their exit slots when the instrument is fired.

FIG. 4 is an isometric view onto the proximal surface of the anvil 4,which includes a peripheral rim 40 and an end plate 42. The proximal endside of the rim 40 is designed as a staple-forming surface 43. For eachstaple, the staple-forming surface 43 comprises a pair of staple-forminggrooves which form or bend the pointed ends of the staple when theseends are pushed against the staple-forming surface 43 upon firing theinstrument.

The relief of the staple-forming surface 43 is essentially a negative ofthe relief of the end surface of end part 7. Thus, in the mounted stateof the anvil 4, the grooves 44, 45, and 46 match to the exit slots 14,15, and 16 of the first closed row 10, and a protrusion 48 between thegrooves 44 and 45 fits into the recess 18, whereas a recess 49accommodates the protrusion 19 when the anvil 4 is close to thecartridge device 2. Similarly, the locations of grooves 50, 51, and 52match to the positions of the exit slots 20, 21, and 22 of the secondclosed row 12.

Generally, the stapling instrument is operated like a conventionalcircular stapler. By moving the anvil 4 towards the cartridge device 2,the tissue ends to be stapled are clamped between the end surface of endpart 7 and the staple-forming surface 43 of the anvil 4. The tissuefollows the stepped shapes of the lines along which the first closed row10 and the second closed row 12 of staples are arranged and is forced byprotrusions like the protrusion 48 or the staple-forming surface 51 onthe anvil 4 into corresponding recesses like the recess 18 or the areaof the exit slot 21, and vice versa. The width of the recesses likerecess 49 or recess 18 is somewhat larger than the width of thecorresponding protrusions like protrusion 19 or protrusion 48, such thatthe tissue is not squeezed in the protrusion/recess pairs.

When the instrument is fired, the staples of the first closed row 10 andthe second closed row 12 are expelled almost simultaneously from the endsurface of the end part 7, penetrate the tissue parts and are formed atthe staple-forming surface 43 of the anvil 4. Immediately afterwards,the cutting edge of the circular knife, which is mounted on the stapledriving device 30 inside the pushers 38 and 39 of the second closed row12, cuts the tissue.

After firing, the distance between the anvil 4 and the cartridge device2 is somewhat increased in order to release the anastomosis seam.Because of the stepped structures of the end surface of the end part 7and the staple-forming surface 43 of the anvil 4, the staple lines ofthe anastomosis seam have a greater length than comparable staple linesresulting from corresponding smooth surfaces in a conventional circularstapler of the same outer diameter. Consequently, retraction of theinstrument is easier.

FIG. 5 is an isometric view onto the proximal surface of the anvil 4′ ofa second embodiment of the surgical stapling instrument. The anvil 4′ isthe counterpart of a cartridge device having two closed raws of staples,in which the designs of the outer closed raw of staples and of the innerclosed raw of staples are reversed with respect to the cartridge device2 of the first embodiment. To facilitate comparison with FIG. 4, in FIG.5 the same reference numerals are used as in FIG. 4, but they areprimed.

The relief of the staple-forming surface 43′ is essentially a negativeof the relief of the end surface of the cartridge device of the secondembodiment. In a corresponding staple driving device, the lengths of thepushers are adjusted to the locations of the staples in the cartridgedevice of the second embodiment. The cartridge device and the stapledriving device of the second embodiment are not shown in the figuresbecause the details are evident from a comparison with the firstembodiment.

1. A surgical stapling instrument having a distal end, a proximal end,and a longitudinal axis therebetween, said instrument comprising: aflame having a body portion and a handle, a staple fastening assembly(1) in the distal region of said instrument, the staple fasteningassembly (1) including a cartridge device (2), said cartridge having adistal surface having a stepped configuration comprising a series ofalternating gaps and protrusions such that said protrusions are distalto said gaps, said cartridge device further comprising at least oneclosed row (10, 12) of staples disposed along said series of alternatinggaps and protrusions, and an anvil (4) which is movable relative to thecartridge device (2) and is adapted to cooperate with the cartridgedevice (2) for forming the ends of the staples exiting from thecartridge device (2), a moving device adapted to move the anvil (4)relative to the cartridge device (2), a staple driving device adapted todrive the staples out of the cartridge device (2) towards the anvil (4),a knife, which has a closed cutting edge, is contained within thecartridge device (2) and is positioned such that there is at least oneclosed row (10, 12) of staples on the outside of the cutting edge, and aknife actuating device adapted to move the knife towards the anvil (4).2. Stapling instrument according to claim 1, characterized in that theanvil (4) has a proximal surface having a stepped configurationcomprising a series of alternating gaps and protrusions which matchesthe stepped configuration cartridge, such that said gaps on saidcartridge match said protrusions on said anvil, and said protrusions onsaid cartridge match said gaps on said anvil.
 3. Stapling instrumentaccording to claim 1, characterized in that said knife has a steppedshape which matches the stepped configuration of said distal surface ofsaid cartridge.
 4. Stapling instrument according to claim 1,characterized in that the staple driving device (30) is adapted to drivethe staples out of the cartridge device (2) such that each staple ismoved essentially in parallel to the longitudinal axis of the staplefastening assembly (1).
 5. Stapling instrument according to claim 4,characterized in that the staple driving device (30) comprises pushers(36, 38, 39) for driving the staples.
 6. Stapling instrument accordingto claim 5, characterized by at least two groups of pushers (38, 39)having different lengths.
 7. Stapling instrument according to claim 5 or6, characterized in that the pushers (36, 38, 39) are integrallycombined in a sleeve structure (30).
 8. Stapling instrument according toclaim 1, characterized in that the staple driving device (30) is adaptedto drive the staples of a closed row (10, 12) of staples essentiallysimultaneously out of the cartridge device (2).
 9. Stapling instrumentaccording to claim 1, characterized by at least two closed rows (10, 12)of staples, wherein the staples of adjacent rows (10, 12) are staggeredwith respect to each other.
 10. Stapling instrument according to claim1, characterized in that the anvil (4) comprises a counterpart adaptedto accommodate the cutting edge of the knife.
 11. Stapling instrumentaccording to claim 1, characterized in that the staple fasteningassembly (1) is removably mounted in the distal end region of the bodyportion.
 12. Stapling instrument according to claim 1, characterized inthat the anvil (4) is removable.
 13. Stapling instrument according toclaim 12, characterized in that the anvil comprises a shaft fitting ontoa peg protruding from the cartridge device, which peg preferablycomprises a mandrel.
 14. Stapling instrument according to claim 1,characterized in that the cartridge device (2) comprises a removablecartridge containing the staples.